Multiblend powder mixing apparatus

ABSTRACT

Apparatus for delivering two or more metallic, ceramic or plastic powders, at any given ratio, through a common manifold to thermal spray equipment permits the production of multiblend or graded coatings.

United States Patent 1191 Janssen Oct. 14, 1975 [5 MULTIBLEND POWDER MIXING 3,361,412 l/l968 Cole 259 4 APPARATUS 3,424,439 l/l969 Baker 259/4 3,462,130 8/1969 J0achim.... 259/4 [75] Inventor: .K nneth T. Janss n, Br k, 3,478,963 ll/l969 Winn 259 5 C011. 3,554,7l4 l/l97l JOhnSOn.... 259/4 3,593,735 7/1971 Reiher 259/4 [73] Asslgneel g Corpwatm, 3,623,704 11/1971 SkObel 259/4 a or onn.

[22] Filed: 1974 Primary ExaminerRobert W. Jenkins [21] A NO 1 534,339 Attorney, Agent, or Firm-Richard N. James [52] US. Cl 259/4; 259/7 511 lm. c1. B01F 15/02 [57] ABSIRACT [58] new of 259/4 Apparatus for delivering two or more metallic, ce-

259/18 ramic or plastic powders, at any given ratio, through a 61; 222/3; 23/252 R common manifold to thermal spray equipment permits [56] R f Cted the production of multiblend 0r graded coatings.

e erences 1 UNITED STATES PATENTS 8 Claims, 2 Drawing Figures 3,236,419 2/l966 Rerner 259/7 g 62 M /Z E E E E Z W 30 7% V .Z A V\ I, rm 16 7 2% 7 W /Z a i U.S. Patent Oct.14,1975 SheetlofZ 3,912,235

US. Patent Oct. 14, 1975 Sheet 2 of 2 &

MULTIBLEND POWDER MIXING APPARATUS BACKGROUND OF THE INVENTION The present invention relates to powder blending apparatus particularly for use with thermal spray equipment. As used herein, thermal spray techniques will be understood to make reference to either flame or plasma spray procedures.

In the generation of coatings by thermal spray techniques it is frequently desirable to provide coatings which are a blend of two or more distinct components. The characteristics of such components may be such that simple preblending in a single hopper is notfeasible, perhaps due to reactivity problems or difficulties in maintaining a uniform blend because of density or particle size differences. Furthermore, it is frequently desirable to provide a coating wherein the composition varies as a function of coating thickness. For example, it is known that ceramic coatings applied directly to metallic substrates often are unduly shocksensitive because of relative differences in thermal expansion between the metal substrates and the ceramic coatings.

In such instances it is desirable to provide a coating which varies, as a function of coating thickness, from metal adjacent the substrate to ceramic at its outer surface. For the above reasons and others, the use of a single source of premixed powder frequently is unsatisfactory in the generation of coatings by thermal spray techniques.

For the development of graded coatings, one alternative involves the use of multiple spraying guns, one gun being phased out while another or others are gradually phased in. Such a technique is disclosed in the US. Pat. No. 3,545,944 to Emmanuelson et al, of common assignee herewith. Such a technique, of course, involves multiple spraying guns.

Another alternative is the technique disclosed in Winzeler et al, US. Pat. No. 3,378,391 wherein multiple feed'lines from separate powder sources are fed into a spray gun of special design and mixed therein.

SUMMARY OF THE INVENTION The present invention relates to powder blending apparatus wherein two or more powders of distinct composition are blended and delivered in a common manifold to thermal spray equipment. In this apparatus powders from separate sources may be delivered into the system in any given ratio or sequence either at a constant rate or at a changing rate.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a somewhat schematic representation of a preferred embodiment of the present invention.

FIG. 2 shows the powder manifold in greater detail.

DESCRIPTION OF THE PREFERRED EMBODIMENTS occurs. A blended powder mixture, typically carried by The principal motive power for the flow of powders from the respective feeders through the manifold to the gun, is provided by a high pressure gas flow. In the drawing, a source of high pressure argon (not shown) is utilized to charge a high pressure gas line 24 through shutoff valve 26. Four separate gas lines are tapped off line 24, specifically lines 30, 32, 34 and 36.

Gas line 30 normally feeds inert gas through a pressure regulator 40, flow meter 42, and normally open solenoid 44 through line 13 to manifold 14 to the gun 22, such as a plasma gun.

The gas lines 32, 34, and 36, which are also tapped off argon feeder line 24 provide a flow of gas through pressure regulators 50, 52 and 54, solenoid valves 56, 58 and 60, and flowmeters 62, 64 and 66. The flow of gas into the respective feeders entrains powders therein, dependent upon the rate of gas flow and therefrom to the gun as previously described.

In the equipment actually constructed, the three powder feeders 2, 4 and 6 were Mark IX Powder Feeders made by Sylvester & Co., Cleveland, Oh. The four pressure regulators 40, 50, 52 and 54 were 0-160 p.s.i. regulators obtained from Nordson Corp., Amherst, Oh. The flowmeters 42, 62, 64 and 66 were all identical and had a capacity of 030 cubic feet per hour. The cyclone mixer was procured from Sylvester and Co., and the spray gun 22 was a Plasmadyne 1068 Minigun.

The powder manifold 14 is shown in greater detail in FIG. 2. The manifold was provided with a central passageway 70 into which four subpassageways 72, 74, 76 and 78 extend at an angle of about 45. Four check valves 80, 82, 84 and 86, such as Parker Model VCL4P1, are connected to the subpassageways by four nipples 90, 92, 94 and 96. Flow through one or more of the subpassageways carrying inert gas and entrained powders from the respective powder feeders enters the central passageway and the gases and mixed powders exit the manifold through line 16.

The above described apparatus is capable of operation in various degrees of sophistication depending upon the desires of the user. In one mode of operation, all of the pressure regulators 40, 50, 52 and 54 are preset to provide desired levels of gas flow through regulators 42, 62, 64 and 66 which in turn regulate the powder amounts fed from the feeders 2, 4 and 6 into the manifold 14 and ultimately to the gun. Argon flow is established through the line 30 and normally open solenoid 44 and thence into the gun 22 without powder entrainment. A powder feed is then initiated closing solenoid 44 and opening one or more of the solenoids 56,

58 and 60. The solenoids 56, 58 and 60 may be all opened simultaneously or sequentially. Solenoid 56 may be programmed to open first, solenoids 58 and'60 remaining closed. Solenoid 58 may then be opened while solenoid 56 is closed, solenoid 60 remaining closed. The sequence may be further repeated with respect to the closing of solenoid 58 and the opening of solenoid 60.

In a further variation the solenoid phase in/phase out operation may be timed such that with solenoid 56 open and all others closed, solenoid 58 may be opened before solenoid 56 closes, providing powders from feeder 2 alone at first, then a mixture of powders from feeders 2 and 4, before solenoid 56 closes, at which time only powders from feeder 4 are provided. The same or different sequencing may be accomplished with the powders in feeders 4 and 6.

In another degree of refinement, the gas flows through the lines 32, 34 and 36 can also be varied during the time gas is flowing therethrough by variation of the settings of the regulators 50, 52 and 54. For example, when solenoid 44 is closed and solenoid 56 is opened, the pressure admitted through regulator 50 may gradually be increased or decreased by opening or closing regulator 50. This may be automatically programmed or may be a simple mechanical adjustment by the operator.

Whatever the sequencing employed in the system or degree of sophistication provided, a blend of powders is provided to the gun 22 through a single manifold, permitting the use of a single feed gun. When the valve sequencing is programmed for the operator he, therefore, need be concerned only with the application of the desired coating thickness, since composition of the coating is automatically controlled by the powder blending apparatus.

Powders admitted through various ports into the manifold 14 are prevented from backing into other ports by the check valves 80, 82, 84 and 86. When switching from one coating system to another, feeders 2, 4 and 6 may be cleaned and reused with the appropriate powders fed thereinto or, of course, substitute containers may be utilized. A gas purge may be utilized to clear the lines of the old powders and substitute feeders can be brought into the system by simply breakprises:

a pluralityof powder feeders each including means for storing powders, a gas inlet, and an outlet for discharging gas and entrained powders therefrom;

means for connecting the individual powder feeder gas inlets to a source of pressurized gas;

regulating means for controlling the gas flow through each connecting means; 1

a powder mixing manifold having a mixing chamber therein, a plurality of inlets to the mixing chamber, and an outlet from the mixing chamber;

entrained powder transmission means interconnecting, for each powder feeder, a powder feeder outlet and a mixing manifold inlet;

gun supply means for connecting the outlet of the mixing manifold to powder spraying apparatus; and

independent gas means for providing a regulated flow of gas from the gas source through the gun supply means, bypassing the powder feeders.

2. Apparatus according to claim 1 wherein:

the regulating means for controlling as flow includes a pressure regulator and a remotely-operable on/- off valve.

3. Apparatus according to claim 2 wherein:

the regulating means also includes a flowmeter.

4. Apparatus according to claim 2 wherein:

the independent gas means is connected between the gas source and an inlet to the powder mixing manifold.

5. Apparatus according to claim 4 wherein:

the independent gas means includes a pressure regulator and a remotely-operable on/off valve.

6. Apparatus according to claim 5 wherein:

the remotely-operable valve is a normally-open solenoid valve.

7. Apparatus according to claim 6 wherein:

the remotely-operable valve in the regulating means is a normally-closed solenoid valve.

8. Apparatus according to claim 1 wherein:

an additional gas/entrained powder mixing means is installed in the gun supply means. 

1. Multiblend powder mixing apparatus which comprises: a plurality of powder feeders each including means for storing powders, a gas inlet, and an outlet for discharging gas and entrained powders therefrom; means for connecting the individual powder feeder gas inlets to a source of pressurized gas; regulating means for controlling the gas flow through each connecting means; a powder mixing manifold having a mixing chamber therein, a plurality of inlets to the mixing chamber, and an outlet from the mixing chamber; entrained powder transmission means interconnecting, for each powder feeder, a powder feeder outlet and a mixing manifold inlet; gun supply means for connecting the outlet of the mixing manifold to powder spraying apparatus; and independent gas means for providing a regulated flow of gas from the gas source through the gun supply means, bypassing the powder feeders.
 2. Apparatus according to claim 1 wherein: the regulating means for controlling as flow includes a pressure regulator and a remotely-operable on/off valve.
 3. Apparatus according to claim 2 wherein: the regulating means also includes a flowmeter.
 4. Apparatus according to claim 2 wherein: the independent gas means is connected between the gas source and an inlet to the powder mixing manifold.
 5. Apparatus according to claim 4 wherein: the independent gas means includes a pressure regulator and a remotely-operable on/off valve.
 6. Apparatus according to claim 5 wherein: the remotely-operable valve is a normally-open solenoid valve.
 7. Apparatus according to claim 6 wherein: the remotely-operable valve in the regulating means is a normally-closed solenoid valve.
 8. Apparatus according to claim 1 wherein: an additional gas/entrained powder mixing means is installed in the gun supply means. 